Embodiments of the inventive concept relate generally to semiconductor memory devices. More particularly, embodiments of the inventive concept relate to overwritable nonvolatile memory devices and related data write methods.
Semiconductor memory devices can be roughly divided into two categories according to whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power.
Examples of volatile memory devices include dynamic random access memory (DRAM) and static random access memory (SRAM). Examples of the nonvolatile memory devices include masked read-only memory (MROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM).
The demand for nonvolatile memory devices has continually increased over the past several decades. Moreover, in recent years, there has been an increasing demand for nonvolatile memory devices that can be used as execute in place (XIP) devices. Accordingly, research is being conducted to develop and improve overwritable nonvolatile memory (NVM) devices.
Examples of overwritable nonvolatile memory devices include ferroelectric RAM (FRAM) using ferroelectric capacitors, magnetic RAM (MRAM) using a tunneling magnetoresistive (TMR) layer, phase-change random access memory (PRAM) using a chalcogenide alloy, and resistive RAM (ReRAM) using a variable-resistance material layer as a data storage medium.